Acrylic acid, which is used as a raw material of an absorbent resin and the like, has been industrially widely produced by gas-phase oxidation of acrolein obtained by gas-phase oxidation of propylene.
In recent years, production of acrylic acid by gas-phase oxidation of a product which has been obtained by gas-phase dehydration of glycerin has been disclosed (refer to Patent Literature 1).
In addition, production of acrolein by dehydration of glycerin is disclosed (refer to Patent Literature 2). The acrolein obtained by this production differs from acrolein which is obtained by gas-phase oxidation of propylene in terms of kinds and quantities of byproducts. Therefore, in order to produce acrylic acid by conducting conventionally-known gas-phase oxidation of a composition containing such acrolein, it is described to be preferable that acrolein is purified by employing a conventionally-known technique (refer to Patent Literature 2).
Further, it is disclosed of a process for producing acrylic acid, comprising the steps of producing allyl alcohol from glycerin and conducting gas-phase oxidation of the obtained allyl alcohol to produce acrylic acid (refer to Patent Literature 3).